macosx/open: replace deprecated API call with modern blocks-based counterpart

modules/gui/macosx/open.h

@@ -266,7 +266,6 @@
 - (void)openFileGeneric;
 - (void)openFilePathChanged:(NSNotification *)o_notification;
 - (IBAction)openFileBrowse:(id)sender;
-- (void)pathChosenInPanel: (NSOpenPanel *)sheet withReturn:(int)returnCode contextInfo:(void *)contextInfo;
 - (IBAction)openFileStreamChanged:(id)sender;
 
 - (void)openDisc;

modules/gui/macosx/open.m

@@ -752,28 +752,16 @@ static VLCOpen *_o_sharedMainInstance = nil;
     [o_open_panel setCanChooseDirectories: YES];
     [o_open_panel setTitle: _NS("Open File")];
     [o_open_panel setPrompt: _NS("Open")];
-
-    [o_open_panel beginSheetForDirectory:nil
-        file:nil
-        types:nil
-        modalForWindow:[sender window]
-        modalDelegate: self
-        didEndSelector: @selector(pathChosenInPanel:
-                        withReturn:
-                        contextInfo:)
-        contextInfo: nil];
-}
-
-- (void)pathChosenInPanel: (NSOpenPanel *) sheet withReturn:(int)returnCode contextInfo:(void  *)contextInfo
-{
+    [o_open_panel beginSheetModalForWindow:[sender window] completionHandler:^(NSInteger returnCode) {
         if (returnCode == NSFileHandlingPanelOKButton)
         {
             if( o_file_path )
                 [o_file_path release];
-        o_file_path = [[[sheet URLs] objectAtIndex: 0] path];
+            o_file_path = [[[o_open_panel URLs] objectAtIndex: 0] path];
             [o_file_path retain];
             [self openFilePathChanged: nil];
         }
+    }];
 }
 
 - (IBAction)openFileStreamChanged:(id)sender